Asthma

Asthma is one of the diseases that doctors have trouble defining,
but recognise when we see it. Physically, asthma is narrowing of
the airways (the air passages in the lung). When these airways
are narrowed they obstruct air flow in and out of the lung,
making it harder to breathe. (It is actually harder to breathe
out than in with asthma and other obstructive diseases;
many of the problems asthmatics have are caused by not being able
to exhale properly, which makes it hard for the body to get rid of
carbon dioxide.) Unlike other obstructive-airway diseases such as
emphysema, the narrowing of asthma can resolve, either by itself or
with treatment. Asthma can be very mild and resolve without
treatment, but people can and occasionally do die of status
asthmaticus (severe asthma with almost continuous airway
obstruction).

Asthma is also known as reactive airway disease.
This is because airway narrowing often occurs as a reaction to an
irritant such as chemical fumes, dust, or airborne allergens.
Tobacco smoke is a notorious, and completely avoidable, cause of
airway narrowing, but any other inhaled allergen -- weed, grass,
tree, and flower pollens, indoor and outdoor molds, insect
droppings, and animal dander, among others -- can cause
airway inflammation and narrowing. (These are the same
allergens that cause
allergic rhinitis, and you can
reduce your
exposure to these allergens just as you would to avoid allergic
rhinitis. Viral infections can also
trigger asthma attacks by inflaming the airways; some patients
have their attacks mainly or only after a viral
cold.
Some people have asthma attacks with no apparent triggers.
There are also people whose asthma attacks are triggered by
moderate or vigorous exercise. These attacks can be
disconcerting if not disabling, but can often be prevented by
taking a bronchodilator before
exercising vigorously. Many well-known athletes (including
Jackie Joyner-Kersee and Amy Van Dyken) have exercise-induced
asthma, and their asthma does not affect their athletic
performance as long as they use their medications properly.

Treatment of Asthma

Treating asthma is largely a matter of reducing the narrowing
in the airways, which allows easier air movement. This can be
done by dilating (widening) the airways, and by reducing
inflammation in the airway walls.

A common way for you and your doctor to measure how well you
are breathing normally or during an attack is the peak
flow meter. This gadget measures how fast you can exhale;
since the airway narrowing of asthma affects expiration more
than inhalation, the peak expiratory flow, or PEF, ,
can tell you how severe the inflammation is. Your doctor may
recommend a peak flow meter to you, and show you how to use it
and what flow rates are signs of impending trouble. In some
cases (usually with experienced patients or parents) your doctor
may suggest different or additional medicines for different
peak flow rates.

Trouble breathing is, of course, a sign of worsening asthma.
An earlier sign in many patients is a cough that worsens or
persists for a while, although this could be a simple cold
as well. I try to listen to the lungs of any known asthmatic
with a persistent cough, since the characteristic wheeze
often cannot be heard without a stethescope. A patient with
asthma who is having trouble talking is having a lot of
trouble moving air, and needs to be seen by a doctor immediately.
Again, your doctor can review other danger signs with you.

Bronchodilators

The fastest way to relieve an asthma attack is with medicine
that makes the airways widen; these medicines are known as
bronchodilators. Your body can do this by itself by
releasing adrenaline, or epinephrine; this not
only cause your heart to pump faster and stronger, but also
makes the airways widen to allow more air to pass (this happens
even if you are not an asthmatic -- it's part of the "fight
or flight" response to danger that's built into all of us).

However, speeding up your heart isn't absolutely necessary in
treating an asthma attack, and may even be harmful in some
cases (although an injection of epinephrine is a perfectly
good emergency treatment for many asthmatics who cannot breathe
well during an attack). For routine and urgent cases, we try
to use medicines similar to epinephrine that widen the airways
but do not speed up the heart as much as epinephrine.
The most commonly used medicine of this sort is albuterol,
which is chemically similar to epinephrine but has much
less effect on the heart than epinephrine does. (Note, though,
that albuterol will speed up the heart to some extent
-- and that it should not be used at the same time as other
similar medicines, including most over-the-counter
decongestants and cold medicines, unless your doctor tells
you to do so.)

Albuterol comes in several different forms. It can be given
orally, as a syrup (for small children) or pills (immediate or
time-release), but albuterol doesn't work all that well if it's
taken by mouth. It can also be inhaled, from a pocket-size
metered-dose inhaler (MDI) or from a nebulizer
which makes a fine mist out of the liquid solution. Inhaled
albuterol doesn't have quite as much heart-speeding effect as
oral albuterol, but it also works a lot faster than oral
albuterol.

There are bronchodilators on the market that are similar
to albuterol but act more slowly. These are often used for
"maintaining" asthmatics who are relatively well-controlled.
Some of these medicines will NOT work fast enough to
stop a severe asthma attack. If you are on one of these
slow-acting bronchodilators, be sure to ask your doctor about
what to do differently in an emergency.

In the past, theophylline was used routinely as a
bronchodilator for asthmatics. Theophylline is chemically
similar to caffeine, and has the same stimulant effects;
both theophylline and caffeine (to a lesser extent --
don't pig out on coffee to treat your asthma) will
help open up air passages, although we're not completely
sure about how they work. Theophylline can be given orally
or through an IV. Albuterol and epinephrine work faster than
theophylline in most patients, and often with fewer side effects,
so at present theophylline is not widely used.

Steroids

Steroids, which are hormones normally produced by your body,
help regulate many bodily functions including inflammation.
Giving extra steroids for a short period of time may help
reduce inflammation; in particular, steroids can help open
an asthmatic patient's airways by reducing the inflammation
in the airway walls. Other steroid hormones help regulate
such things as reproduction, blood pressure, and mineral
balances (like sodium and potassium, which are crucial to
many important functions) as well as body development and
growth.

Steroids have their drawbacks. Your body must make
steroids all the time for many processes to work right. If
you take steroids for too long, your steroid-making system
will think it's not needed any more and shut down, and if you
then face a situation where you need the steroids (any kind
of stress, including surgery) all sorts of things can go wrong
-- like your blood pressure, to take one example.

When we give steroids to asthmatics, we can do so orally (very
convenient), through an IV line (which actually doesn't work
any faster than oral in many patients -- but if you are having
so much trouble breathing that you can't take the time to
swallow, it might be useful), or by inhalation (either with
a nebulizer or with a metered-dose inhaler). Inhaled
steroids are nice for long-term treatment of asthmatics because
the medicine tends to stay in the lungs, and so the side effects
on the rest of the body aren't as bad. In more severe
asthmatics we will occasionally give 3-5 day "pulse" treatments
with oral steroids. If we give steroids for longer than that
the body starts getting lazy about making its own, and so we
have to "taper" the dose over a few days at the end. Even so,
some bad asthmatics may become steroid-dependent if they have
to take steroids often enough. (On the other hand, if you're
an asthmatic who needs steroids now, you may not have
the luxury of worrying about the long-term effects until your
breathing is better.)

Leukotriene Esterase Inhibitors

Leukotriene esterase is an enzyme that is part of our bodies'
immune system, and which helps inflammation happens. Drugs such as
zafirlukast and montelukast block this enzyme and so make inflammation
less likely to happen. In this respect they are like cromolyn,
but their mechanism is very different. Like cromolyn, these
medicines must be taken regularly, and they will not
relieve an asthma attack in progress -- you will still need the
fast-acting bronchodilators.

PLEASE NOTE: As with all of this Web site, I try to give
general answers to common questions my patients and their parents ask me
in my (real) office. If you have specific questions about your
child you must ask your child's regular doctor. No doctor can give
completely accurate advice about a particular child without knowing and
examining that child. I will be happy to try and answer
general questions
about children's health, but unless your child is a regular patient of
mine I cannot give you specific advice.